Here's my take:
If you are the typical occasional camper, doing 3-4 short trips and maybe 1 long trip every year or 2, then you can life with being closer to your limits. Not saying your should go over any limits. But the added cost of having more cushion isn't worth it (?). Maybe better to have the 1500 for the 95% of miles you drive without the trailer.
On the other hand, a full-time RVer, or someone who plans to do lots of long runs might want an easier tow with a HD/Superduty truck. A diesel will get better gas mileage under towing duty, and give more confidence when trailer towing is more in the 30-50% of driving.
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller